Fast optical switching has remained an unsolved problem for mode fiber optic communication and sensor networks. Slow opto-mechanical switches are known in which the free end of an optical fiber is movable from one station to another. At each station, the movable end is aligned with the fixed end of another optical fiber. Such opto-mechanical switches operate at slow speeds (in the order of 10 milliseconds) which severely limit their utility. Moreover, repeated flexure of the movable free end of the optical fiber tends to induce fatigue and ultimately results in breakage of the fiber.
In contrast to the presently available optical switches, semiconductor electronic switches are available which switch electrical signals at the high speeds required in communication networks. Fiber-optic analogs of those high speed electronic switches have yet to become available.
The short term solution to the lack of higher speed optical switches has been to convert the optical signals into electrical signals prior to switching by electronic switching devices and then to reconvert the electrical signals into optical signals, after switching, for transmission along optical fibers. However, electronic switches are susceptible to the effects of electromagnetic interference which can prevent those switches from operating reliably. In addition, the electrical conductors which carry the electrical signals to and from the electronic switches are also affected by electromagnetic interference. Consequently, both the reliability of the electronic switch as well as the integrity of the electrical signals transmitted through the switch can be adversely affected by electromagnetic interference.
An optical switch offers inherent immunity to the effects of electromagnetic interference. The optical signals transmitted along the optical fibers are not perturbed by electromagnetic interference. Systems which use optical switches are able to operate reliably in environments where electronically switched systems have proved to be unreliable. Moreover, optical switches are more compatible with optical fiber networks than are electronic switches inasmuch as optical fibers can be connected directly to optical switches without requiring the intervention of converters to change the optical signals to electrical signals.